1. Field of the Invention
This invention relates to vertical lift gates used to control the access of a pathway. More specifically, this invention relates to electrically powered vertical lift gates which are activated manually or through the use of remote controls and sensors.
2. Prior Art
Vertical lift gates have been in use more than a century, as evidenced in U.S. Pat. Nos. 391,734 to A. H. Broad and 606,250 to S. Stout. Obstructions on either side of the gate, such as livestock, vehicles, or snow, do not affect the operation of vertical lift gates. This allows vertical lift gates to be used in areas where conventional swing gates are not practical. Many variations of the same basic vertical lift gate design have been patented through out the years.
U.S. Pat. Nos. 391,734 to Broad; 798,846 to Van Pelt; 1,672,723 to McClary; 2,083,855 to McReynolds; 2,563,894 to White; 2,807,107 to Goulet; 3,823,510 to Panaccione; 4,519,164 to Porter; and 4,658,543 to Carr all teach gates that expand as they are lowered and collapse together as they are raised. Most of the early designs require many moving parts, including large counterbalance weights, overhead mechanisms, ropes, pulleys, large gears, and vehicle ramps. These early designs are large in size and their many moving parts require regular maintenance for proper operation. In contrast, modern designs eliminate overhead mechanisms, counterbalance weights, and vehicle ramps.
All of the prior designs partially obstruct the pathway when in an open position, with the exception of U.S. Pat. Nos. 3,823,510 to Panaccione and 4,519,164 to Porter. U.S. Pat. Nos. 391,734 to Broad; 798,846 to Van Pelt; 1,672,723 to McClary; 2,083,855 to McReynolds; 2,563,894 to White; 2,807,107 to Goulet; 4,658,543 to Carr are all incapable of opening to a true vertical position due to the mechanics incorporated into the various collapsing gate designs. These gates comprise two categories:
Gates with two or more horizontal rails that are all pivotally mounted at one end to a gate post and are also connected by vertical members. PA1 Gates with a single horizontal support rail pivotally mounted at one end to a gate post and to which lower horizontal rails are attached and hang freely from vertical members.
The gates of the first category are prevented from opening to a true vertical position when a lower rail contacts the pivot point of an upper rail, the vertical members prevent the horizontal rails from coming together, or the counterbalance weight contacts the gate post. This is shown in U.S. Pat. No. 4,658,543 to Carr, where the vertical members 19 prevent the horizontal spars 17 & 18, as viewed in FIGS. 1 & 2, from coming together and achieving a true vertical position.
The gates of the second category are prevented from opening to a true vertical position due to the counterbalance weights contacting the gate posts or in the case of U.S. Pat. No. 1,672,723 to McClary, the left most vertical bar 17, as viewed in FIG. 4, contacting the post 10, prevents the gate from achieving a true vertical position.
All of these gates, when open, partially obstruct the pathway and this forces the use of a wider than normal gate. More specifically, if a minimum of 10 feet is required for passage, then the actual width of the gate must be greater than 10 feet, as either the lower rail or the raised end of the gate protrudes into the pathway. These prior designs are unsuitable for replacements to conventional swinging gates when space is limited and the current width of the pathway must be maintained.
U.S. Pat. Nos. 3,823,510 to Panaccione and 4,519,164 to Porter, teach gates which open to a true vertical position. However, the Panaccione gate operating mechanism is very complex and uses several motors which increases the need for maintenance. The rails of the Porter gate are offset and do not "hang" directly below one another. This creates a stair step effect when the gate is in a closed position and requires more space as compared to other designs. This design also requires the enclosure containing the gate operating mechanism to be open on at least one side. This design is unsuitable in climates where weather is severe and snow or rain may be blown into the enclosure, interfering with normal operation. In addition the Porter gate has many moving parts, including chain drives, rigid links, cams, pulleys and cables.
Another problem with the prior designs is the enclosures containing the gate operating mechanisms. The older designs did not enclose the gate operating mechanisms because they were too large and it would have been impractical. However, the modern designs do enclose the gate operating mechanisms, but these enclosures are large. This compounds the problem of using these gates as replacements for conventional swing gates, where space is limited. U.S. Pat. No. 4,658,543 to Cart, shows a large enclosure attached to a support post containing the gate operating mechanism. This requires much more space than a conventional gate post and makes this design especially unsuitable for use as a replacement gate.
Whatever the merits, features, and advantages of the above cited references, none of them achieves or fulfills the purposes and objectives of the current vertical lift gate of the present invention.